FIG. 1 is an illustration of a biaxially cast twin cavity CM block 30a formed with a biaxial CM casting apparatus depicted in FIGS. 9-11 which is also disclosed in my above '342 application, the disclosure of which is hereby incorporated by reference herein in its entirety. Biaxial cast CM block 30a comprises longitudinally parallel face shells 31 interconnected by two laterally extending end webs 32a and a center web 34a. The face shells 31 and the three webs 32a, 34a form two cavities 35 which extend through the block 30a from the top 37 to the bottom 38 thereof in the direction of the flow of CM material during casting of biaxially cast CM block 30a.
The biaxially cast CM block 30a differs from a conventional CM block in that there are openings or apertures 40 extending through each of the end webs 32a and the center web 34a with the axis of each opening 40 being substantially normal to the direction of material flow during casting (i.e., the "axis of casting"). The openings 40 in the webs 32a and 34a are made by varying the mold aperture during casting and timing such variations of mold aperture to result in variation of the shape of the CM block 30a by providing openings 40 which are formed normal to the axis of casting without a secondary manufacturing operation, as further below explained.
The openings 40 in webs 32a and 34a are located on, the block's vertical center line which is mid-way between the outer surfaces of block face shells 31; and the center of openings 40 may also be located at or slightly below the block's horizontal center line which is at the vertical mid-point of the block between the top and bottom thereof.
With reference to FIGS. 10, the biaxial CM mold core system 41 as disclosed in my aforesaid application includes a pair of mold core assemblies 42,44 plus a core bar assembly 46 for installing the system 41 in a commercially available CM block casting machine 48 as depicted in FIG. 11, plus air supply means 50 for pneumatically operating the mold core assemblies 42 and 44. More specifically, the casting machine 48 includes a four-sided mold box with four vertically extending walls 54 at right angles to each other. Casting machine 48 also includes a compression and stripper shoe 56, a material feed tray 58, a strike off bar 59 and means for raising a pallet 60 to form the bottom of the mold for casting a CM block as generally known in the art and as hereinafter discussed.
Each mold core assembly 42,44 includes a generally rectangular shaped mold core 49 having opposing pairs of planar vertical side walls 51 and 53,53a, plus a horizontally disposed planar top end wall 55, and an open bottom 57 (FIG. 13). Mold cores 49 are similar to conventional mold cores used to make conventional twin cavity CM blocks, however, each mold core 49 is modified by cutting axially aligned circular apertures 59 in opposite sides 53, 53a thereof (FIG. 9). A cylindrical assembly sleeve 62 is disposed within each mold core 49 with opposite ends thereof mounted in apertures 59 in opposing side walls 53,53a. An "inner" axially reciprocating plunger 64 is mounted in one end of cylinder 62 in each mold core assembly 42 and 44 so that (1) each plunger 64 can be retracted inside of adjacent walls 53a of its mold core 49 as shown at the right of FIG. 9; and so that (2) such plunger 64 can project outside of the mold core walls 53a as shown at the left in FIG. 9. Another somewhat longer "outer" axially reciprocating plunger 66 is mounted in the other end of cylinder 62 of each mold core assembly 42,44 so that each plunger 66 can also be retracted inside of adjacent wall 53 of its mold core 49 a shown at the right of FIG. 9; and so that these plungers 66 can project outside of walls 53 as shown at the left in FIG. 9. The construction and mode of operation of the axial plungers 64,66 are the same in each mold core assembly 42 and 44.
In the preferred embodiment, the axial plungers 64 and 66 are energized to extend and retract by compressed air means although equivalent mechanical means, electromechanical means, hydraulic means, or a combination thereof, may also be utilized.
Reference is now made particularly to the schematic or diagrammatic drawings of FIGS. 2-8 which show components of a biaxial CM casting apparatus in various phases of a biaxial CM casting process for making biaxial CM blocks like 30b (or 30a, using end cores) by utilizing the present inventions herein.
Referring to FIG. 2, this is a schematic or diagrammatic illustration showing a biaxial CM mold core system 41 installed in the mold box 52 of the CM casting machine. The sides 53 of mold core assemblies 42 and 44 are disposed adjacent to, but suitably spaced from the two shorter sides 54 of mold box 52; and the sides 51 of mold core assemblies 42 and 44 are disposed adjacent to, but suitably spaced from the two longer sides 54a of the mold box 52. The other sides 53a of each mold core 49 of mold core assemblies 42 and 44 are inwardly disposed adjacent to but spaced from each other a suitable distance. Each of the plungers 64 and 66 of mold assemblies 42 and 44 is wholly retracted within the side walls 53 and 53a of its mold core 49. FIG. 2 shows a phase of operation of the biaxial CM casting apparatus and a step in the biaxial CM casting method according to both my prior and the present invention wherein the feed tray 58 containing the semifluid CM mix is off to the side of the mold 52, the compression/stripper shoe 56 is being moved on its way up to provide access for the feed tray 58 to the mold 52 and a conventional bottom pallet 60 is being moved upward to form the bottom of the mold 52.
In FIG. 3, the bottom pallet 60 forms the bottom of the mold 52, and the compression/stripper shoe 56 is above the level of the feed tray 58 which is moving into position over the mold box 52 for purposes of feeding the semifluid CM mix into mold 52. In this phase, all axial plungers 64 and 66 are caused by compressed air to project in extended position from the mold cores 49 so that the ends 67 of the longer axial plungers 66 abut against adjacent side walls 54 of the mold box 52 and the ends 65 of the shorter axial plunger 64 abut against each other.
In FIG. 4, semifluid CM mix 70 is fed into the cavity of mold 52 while axial plungers 64 and 66 are still extended from the mold core assemblies 42 and 44.
In FIG. 5, the feed tray 58 has been laterally withdrawn from its position over the mold 52 permitting a strike off bar 59 to pass horizontally above and in substantially scraping contact with the top end walls 55 of the mold core assemblies 51 so as to remove excess CM material extending upwardly from the cavities above the plane of the top end walls. Thereafter, compression/stripper shoe 56 comes down and compresses the CM mix 70 in the mold 52 as vibration of the mold proceeds by conventional means incorporated in CM casting machine 48. During this phase of operation said axial plungers 64 and 66 remain extended from the mold cores 42 and 44 to prevent CM mix 70 from filling in the spaces in mold 52 thus occupied by the portions of said extended plungers 64 and 66 projecting from both mold cores 49. This causes the formation of openings 40 in end webs 32b and in center web 34a of the biaxially cast CM block 32b shown in FIG. 1 (this is in contrast to conventionally cast twin-cavity CM blocks which have solid end and center webs due to use of conventional mold cores that do not incorporate axial plungers 64 and 66, or other equivalent means.)
In FIG. 6, the axial plungers 64 and 66 are in the process of being retracted by compressed air to dispose said plungers 64 and 66 inside the walls of the mold cores 49 after completion of the block compression phase of the process described above with reference to FIG. 5.
In FIG. 7, the axial plungers 64 and 66 are fully retracted to within the side walls of the mold cores 49, whereby the compressed CM material formed into CM block 30b having three web openings 40 can be and is stripped from the cavity of mold 52 by simultaneous downward motion of the compression/stripper shoe 56 and bottom pallet 60.
In FIG. 8, the compression/stripper shoe 56 returns upward past the mold core assemblies 42 and 44 and their axial plungers 64 and 66 which are retracted within the side walls of the mold cores 49, while the newly made biaxially cast CM block 30b is being ejected on its individual pallet 60 onto a conveyor.
After the compression/stripper shoe 56 moves upwardly out of and above the mold 52 the above-discussed steps of FIGS. 2-8 then may be and are repeated to carry out the next cycle for molding the next CM block 30b in like manner.
The core bar assembly 46 and mounting system includes a conventional type commercially available core bar assembly comprising an elongated core bar 72 which has a configuration as shown in FIGS. 9-11 and is welded to the top end wall 45 of each of mold cores 49 (core bar 72 is usually made from high strength steel about one-half inch thick). Core bar 72 has a pair of mounting brackets 74 welded to its ends and extending perpendicular to the longitudinal axis of core bar 72. Each of mounting brackets 74 is provided with a pair of holes 75 for receiving four machine screws 76 to lock the CM mold core system 41 in place within mold box 52 to provide a biaxial CM casting mold for carrying out the biaxial CM casting process according to the present inventions.
Reference is now made especially to FIG. 9 for detailed description of mold core assemblies generally indicated by numerals 42 and 44. As previously noted, for convenience in disclosure of the invention herein, mold core assemblies 42 and 44 are the same in construction and mode of operation, but mold core assembly 42 is shown at the left of FIG. 9 with plungers 64 and 66 thereof extended, whereas mold core assembly 44 is shown at the right of FIG. 9 with plungers 64 and 68 retracted. It also is noted that, for convenience in disclosure of the invention herein, certain features of said like mold core assemblies 42 and 44 are shown in the mold core assembly 42 at the left of FIG. 9 but are not shown in the mold core assembly 44 at the right of FIG. 9, and vice versa. (Features within the scope of the preceding sentence are noted in description of mold core assemblies 42 and 44 with reference to FIG. 9.) It is further noted that, for convenience of disclosure of the invention herein, some features of each of like mold core assemblies 42 and 44 are shown in the section drawings of FIG. 9, in the same plane, whereas in actual construction some such features are not in the same plane but are angularly or otherwise displaced with respect to the longitudinal axis of cylindrical assembly sleeve 62. (Features within the scope of the preceding sentence are noted in description of mold core assemblies 42 and 44 with reference to FIG. 9.)
Still referring especially to FIG. 9, there is centrally disposed within cylindrical assembly sleeve 62 an elongated cylindrical manifold member generally indicated at 78 which extends through the central aperture of an annular-shaped ring generally indicated at 80. Ring 80 supports manifold member 78 and its related components; manifold 78 and ring 80 are in turn supported within the cylindrical assembly sleeve 62 (sometimes called "assembly cylinder 62" or "plungers assembly cylinder 62"). When assembled, cylinder 62, cylindrical manifold member 78 and annular-shaped manifold supporting ring 80 have substantially coincident longitudinal central axes.
The annular manifold support ring 80 is secured to the assembly cylinder 62 in the interior thereof by a plurality of machine screws like 81 extending through circumferentially spaced apertures 82 in the same plane in the wall of assembly cylinder 62 and respectively threaded into a plurality of drilled and threaded holes like 84 which extend radially into annular ring 80 from its outer periphery.
Manifold member 78 which extends through and is supported in the central aperture 83 of annular ring 80 also is laterally secured to ring 80 by a pair of like retaining rings 86 held in circular recessed grooves extending into the outer periphery of manifold member 78 on opposite sides of manifold support ring 80. The manifold member 78 is provided at each of its opposite ends with a reduced diameter hub 85 which is externally threaded at 85a. An annular stationary piston member generally indicated at 87 is secured to each of the opposite ends of manifold member 78 by means of threads in the central aperture 88 of piston members 87 mating with threads 85a on each of hubs 85 at the opposite ends of manifold member 78. Each stationary piston member 87 is provided on its outer cylindrical periphery with an annular recessed groove 89 in which there is mounted any suitable commercially available annular sealing ring (or rings) shown at 90. Each stationary piston member 87 also is provided on its outer cylindrical periphery with an annular flanged section 91 which has an annular planar end 92 disposed perpendicular to the longitudinal axis of cylindrical stationary piston 87. The axis of stationary piston 87 is coincident with the above-described axes of assembly cylinder 62, ring 80, and manifold member 78.
Cylindrical axial plungers 64 and 66 in each of mold core assemblies 42 and 44 are of like configuration excepting that axial plungers 66 are longer than axial plungers 64 in the direction of their longitudinal axis. Also axial plungers 64 and 66 are mounted on their respective coacting stationary pistons 87 in the same way and operate in relation thereto in like manner as herein described. Each axial plunger 64 is provided with an internal hollow cylindrical portion 93, and each axial plunger 66 is provided with an internal hollow cylindrical portion 93a which is like said portion 93 of axial plunger 64 excepting that 93a is longer than 93. The open end of each of cylindrical portions 93 and 93a of axial plungers 64 and 66 is provided with an internal cylindrical step section 94 which in turn is provided with an internally recessed annular groove 95 near the open ends of hollow cylindrical portions 93 and 93a of axial plungers 64 and 66 respectively. An annular ring 96 is mounted in internally stepped section 94 of each of axial plungers 64 and 66; and each said annular ring 96 is secured with one flat side thereof abutting annular face surface 92 on the end of cylinder flange portion 91 of each stationary piston 87, by means of retaining rings 97 disposed in said annular grooves 95. Each of said annular rings 96 is provided with a groove 98 on its exterior cylindrical surface and with a groove 99 on its interior cylindrical surface 97; and suitable commercially available sealing rings 100 are mounted in each of said grooves 98 and 99.
Annular grooves 102 are provided adjacent opposite ends of each assembly cylinder 62 in the interior cylindrical surface 103 of cylinder 62. Sweeper gaskets 104 are provided in each of said grooves 102 and each gasket engages the exterior cylindrical surface of associated axial plungers 64 and 66 so that when plungers 64 and 66 have been extended and exposed to CM mix 70 as shown in FIG. 4, and said plungers are then retracted to inside the mold cores 49 as shown in FIG. 6, the sweeper gaskets 104 will wipe particles of CM mix off the cylindrical exteriors of plungers 64 and 66.
At least the exterior of axial plungers 64 and 66 including their respective ends 65 and 67 may be coated with a sufficient thickness of a commercially available hard and abrasion-resistant chromium-steel alloy or like suitable material.
Referring now to FIGS. 9 and 12, each of like manifold members 78 of mold core assemblies 42 and 44 is provided with a pair of drilled holes 108 and 109 extending longitudinally through manifold member 78 from end to end, spaced from and substantially parallel to the axis of member 78. Each manifold member 78 is also provided with a pair of drilled holes 110 and 112 extending inwardly from the outer periphery of manifold member 78 so that hole 110 intersects said longitudinally extending hole 108 in manifold member 78, and hole 112 intersects longitudinally extending hole 109 in manifold member 78. Also each manifold member 78 is provided near each opposite end thereof with a pair of drilled holes 114 and 116 extending inward from the outer periphery of manifold member 78 and intersecting said longitudinally extending hole 108 in each manifold member 78. Also, the opposite ends of hole 108 in each manifold member 78 (but not hole 109 thereof) are sealed by plugs shown at 113 in mold core assembly 42 at the left of FIG. 9. Referring especially now to mold core assembly 42 at the left of FIG. 9, said holes 114 and 116 are located adjacent each of stationary pistons 87 at the opposite ends of manifold member 78 so that compressed air will pass from end-sealed manifold hole 108 through holes 114 and 116 to the sealed-off space 118 between the stationary piston 87 and the sealed annular ring 96 secured to each of axial plungers 64 and 66. As a result, compressed air injected into the sealed-off spaces 118 via manifold hole 108 and said holes 114 and 116 will apply positive force to axial plungers 64 and 66 causing them to move from the extended position shown in mold core assembly 42 at the left of FIG. 9 to the fully retracted position of plungers 64 and 66 shown in the mold core assembly 44 at the right of FIG. 9. To cause plungers 64 and 66 to extend, compressed air injected via manifold member hole 109 through the open ends thereof into spaces 117 and 119 of plungers 64 and 66 will apply positive force to the axial plungers 64 and 66 causing them to move from retracted position shown in mold core assembly 44 at the right in FIG. 9 to the fully extended position of plungers 64 and 66 shown in the mold core assembly 42 illustrated at the left of FIG. 9.
Still referring particularly to FIGS. 13 and 12, a top portion of ring 80 is milled to provide a recessed cavity 120 having a bottom surface 122 which will be disposed substantially horizontally when the plungers sub-assembly 45 is assembled in mold core 49. A pair of holes 110a and 112a are drilled in ring 80 inwardly from surface 122 of recess 120 in ring 80 so that when each ring 80 is assembled on its associated manifold member 78, said hole 110a in ring 80 is a continuation of hole 110 in member 78 and said hole 112a in ring 80 is a continuation of hole 112 in member 78. Each cylindrical assembly sleeve 62 is provided with drilled holes 110b and 112b which are respectively substantially axially aligned with said holes 110+110a and 112+112a. The top wall 55 of each mold core 49 is provided with drilled holes 110c and 112c which are disposed substantially vertically above holes 110b and 110c in cylindrical assembly sleeve 62. It is noted that holes 110c and 112c are located on opposite sides of core bar 72.
An air coupling block 124 is welded or otherwise secured to core bar 72 above holes 110c and 112c in mold core 49 of mold core assembly 42; and an air coupling block 126 is similarly secured to core bar 72 above holes 110c and 112c in mold core 49 of mold core assembly 42. Metal tubes 128 of suitable material and size for conducting compressed air are disposed on opposite sides of core bar 72 and tubes 28 are connected at one end by press-fit or in other suitable manner to air passage holes 130 and 134 drilled in air coupling blocks 124 and 126 respectively. Each of air tubes 128 extends through hole 112c in top plate 55 of one of mold cores 49 and through hole 110b in one of cylindrical assembly sleeves 62 and has its other end press-fitted in the upper enlarged portion of hole 112a in one of annular rings 80. The lower ends of air tubes 128 are also sealed by O-ring 129 and retainer means 131 disposed in recessed cavity 120 in ring 80 inside assembly cylinder sleeve 62. Thus compressed air fed via each coupling block 124 and 126, respectively, through its associated air tube 128 will pass through hole 110 in manifold member 78 and then via longitudinally extending hole 108 through the open ends thereof to operate axial plungers 64 and 66 so that they will extend. Similar metal tubes 132 for conducting compressed air are disposed on opposite sides of core bar 72, and tubes 132 are suitably connected at one end to air passage holes 135 and 143 drilled in each of air coupling blocks 124 and 126 respectively. Each metal tube 132 extends through a hole 110c in top plate 55 of each mold core 49 and hole 110b in associated cylindrical assembly sleeve 62; and each tube 132 has its other lower end press-fitted in the upper enlarged portion of step hole 110a in annular ring 80. The lower ends of each of air tubes 132 are also sealed by an O-ring (like O-ring 129) and said retainer means 131 disposed in recessed cavity 120 in ring 80 inside assembly cylinder sleeve 62. Thus compressed air fed via air coupling blocks 124 and 126 respectively through tubes 132 will pass through hole 110 into longitudinally extending end-plugged hole 108 of each manifold member 78 to operate axial plungers 64 and 66 so that they will retract as elsewhere herein explained. Retainer means 131 for O-rings 129 is a plate secured in recess 120 in ring 80 by a plurality of screws (not shown) which are threaded into holes extending inwardly into ring 80 from the bottom of 122 of recess 120 (holes not shown).
Air coupling block 124 is provided with another drilled hole 136 perpendicular to and intersecting hole 130 therein and also extending through to the other side of block 124. Air coupling block 124 is provided with still another hole 138 drilled therein perpendicular to and intersecting hole 135 in block 124 and also extending to the other side of the block 124. The other air coupling block 126 is provided with a hole 140 drilled therein perpendicular to and intersecting hole 134 to form an air conduit therewith. Air coupling block 126 is also provided with another hole 142 drilled therein extending normal to and intersecting the hole 143 drilled in block 126 to provide an air conduit therethrough. An air tube 148 is similarly suitably connected at opposite ends thereof to the air hole 136 drilled in air coupling block 124 and to the air hole 140 drilled in air coupling block 126. Also, an air tube 150 is suitably connected at one of its ends to the other end of hole 138 in air coupling block 124, and the opposite end of air tube 150 is suitably connected to air hole 142 in air coupling block 126. Air tubing 144 is connected to a source of constant pressure compressed air through a suitable commercially available three-way valve or like suitable means 48v, and is press-fit or otherwise suitably connected at one end in hole 136 in air coupling block 124. Air tube 146 is similarly connected to a constant pressure compressed air source and suitable commercially available three-way valve or like suitable means 48v, and is press-fit or otherwise suitably connected in the slightly enlarged end of hole 138 in air coupling block 124.
When the compressed air control means such as a three-way valve 48v is operated to provide compressed air to conduit 144 from a conventional compressed air source by suitable conventional means like a three-way valve, the compressed air will be supplied at the same time to both axial plunger sub-assemblies 45 of mold core assemblies 42 and 44 since they are connected in parallel to the compressed air source via conduit 144 whereby the plungers 64 and 66 of mold core assemblies 42 and 44 will simultaneously be extended outwardly to the position shown in mold core assembly 42 at the left of FIG. 9 and in FIGS. 3-5. More specifically, compressed air from conduit 144 passes to conduit 128 of mold core assembly 42 and simultaneously to conduit 128 of mold core assembly 44 via tubing 148 interconnecting air couplings 124 and 126. The compressed air passes simultaneously via tubes 128 to and through holes 112a in ring 80 and 112 in manifold 78 and then through longitudinally extending hole 109 in manifold 78 and out through the open ends of hole 109 into the inside portions 117 and 119 of axial plungers 64 and 66, respectively, causing said plungers to extend under the positive force exerted thereon by compressed air in the manner described. When the compressed air control means such as a three-way valve 48v is alternatively operated to provide compressed air to conduit 146, compressed air will be provided at the same time to each of mold core assemblies 42 and 44 simultaneously. In this case, the compressed air from conduit 146 passes via air coupling block 124 to and through tube 132 to mold core assembly 42, while compressed air simultaneously passes from conduit 146 via air coupling 126 through tubing 150 and air coupling 126 and through air tubing 132 to mold core assembly 44, whereby plungers 64 and 66 will simultaneously be retracted to the position shown in mold core assembly at the right in FIG. 9 and in FIG. 6. More specifically, the compressed air simultaneously provided through tubing 132 to each of mold core assemblies 42 and 44 passes through holes 110a in ring 80 and hole 110 in manifold member 78 and then into and through the end-plugged longitudinally extending hole 108 in manifold member 78, and thence through laterally extending passages 114 and 116 into the spaces 118 behind stationary pistons 87 so as to apply a force which positively and simultaneously retracts all of plungers 64 and 66 in both of the mold core assemblies 42 and 44.
Referring to FIGS. 9 and 13, the bottom portion of each assembly sleeve 62 and annular ring 80 in each of mold core assemblies 42 and 44 is provided with a pair of communicating slots shown at 152 so as to provide an air passage from the inside to the outside of assembly sleeve 62 in communication with the inner portions of axial plungers 64 and 66 disposed on opposite sides of ring 80 in each of mold core assemblies 42 and 44. Such slots 152 provide passages for venting of air from inside sleeve 62 and relief of pressure when the axial plungers are operated as herein explained to cause axial plungers 64 and 66 to move from the extended to the retracted position.
A hole 154 is drilled in the cylindrical wall of each of the longer axial plungers 66 and a smaller vent hole 156 is provided at the end of hole 154 extending to the outer end surface 67 of each of plungers 66. Like holes 154a and 156a are drilled in the cylindrical wall of each of the shorter axial plungers 64. In each of mold core assemblies 42 and 44, a cylindrical pin 158 is mounted at one end on annular support ring 80 in any suitable manner, e.g., by the end of pin 158 being threaded and secured in a threaded hole in ring 80 (see mold core assembly 42 at the left of FIG. 9). The axis of pin 158 is substantially perpendicular to ring 80 and also is coincident with the axis of holes 154,156; and the diameter of pin 158 is less than the inside diameter of hole 154. Thus, air may be vented through holes 154,156 when axial plunger 66 is retracted from the extended position shown in mold core assembly 42 at the left of FIG. 9 to the retracted position shown in mold core assembly 44 at the right of FIG. 9. The pins 158 have an outer diameter also less than the inner diameter of outer holes 156 at the ends of holes 154 in axial plungers 66 so that the ends of pins 158 will extend into holes 156 and thereby clear from said holes any particles of CM mix 70 which may have entered holes 156 during any of the biaxial CM block casting steps described above. Similar but shorter pins 158a are similarly mounted on opposite sides of ring 80 in each of mold core assemblies 42 and 44, and pins 158a extend into apertures 154a in the sides of axial plungers 64, with the ends of pins 158a extending into end apertures 156a when the shorter axial plungers 64 are fully retracted. Pins 158a coact with holes 154a,156a in the shorter axial plungers 64 to vent air when plungers 64 are retracted and also to displace any particles of CM mix 70 which may become lodged in the end holes 156a, in like manner as explained above with reference to longer pins 158 and holes 154,156 of longer axial plungers 66.
After the CM mix 70 is compressed and vibrated to form the CM block 30b as shown in FIG. 5 and retraction of plungers 64 and 66 is started as shown in FIG. 6, there will be resultant substantial negative pressure and vacuum effect between (i) the ends 67 of longer axial plungers 66 and the sides 54 of the mold box 52 and (ii) between the two abutting ends 65 of the shorter axial plungers 64. The holes 154,156 in the longer axial plungers 66 and the holes 154a,156a in the shorter axial plungers 64 serve to break such negative pressure and vacuum effect between the ends 67 of plungers 66 and mold walls 54 and between the abutting ends 65 of the plungers 64 when said plungers start to retract as illustrated in FIG. 6. Also, when the plungers 64 and 66 are being fully retracted after completion of the step shown in FIG. 6 and before start of the step shown in FIG. 7, the ends of pins 158 and 158a will respectively extend into holes 156 of plungers 66 and into holes 156a of plungers 64 to dislodge particles of CM mix therefrom and thereby clean the ends of holes 154,156 and 154a,156a.
Each of biaxial plunger sub-assemblies 45 of each of mold core assemblies 42 and 44 is mounted in its associated mold core 49 by a bracket 160 having a relatively elongated main section 162 and two legs 164 extending substantially perpendicular from section 162 as will be apparent from said Figures. The elongated portion 162 of bracket 160 is secured to a bottom portion of assembly sleeve 62 by a pair of screws 166 extending into threaded apertures 168 in the main portion 162 of bracket 160. Each leg 164 of bracket 160 is provided with a threaded aperture 170 which receives a threaded screw member 172 which is provided with a slot 174 (or equivalent means) to enable turning of screw 172 in threaded aperture 170. A nut 176 is screwed onto the threads of screw 172 on the inside of bracket legs 164 as shown in said Figures. After the biaxial plunger sub-assemblies 45 are mounted in apertures 59 in the walls 53 and 53a of mold core assemblies 42 and 44, respectively, bracket 160 is secured to the assembly sleeve 62 by means of screws 166 threaded into holes 168, and then the screws 172 plus nuts 176 are adjusted in relation to bracket legs 164 and side walls 53 and 53a of the mold core 49 so as to finalize the location of each biaxial plunger sub-assembly 45 in relation to side walls 53 and 53a of mold cores 49 and to secure each bracket 160 firmly in relation to its mold core 49. Each respective biaxial plunger sub-assemblies 45 is thus secured by like bracket means in like manner to the associated mold core 49 of each mold core assembly 42 and 44. It is noted that the slots indicated at 152 cut in the underside of each of assembly cylinders 62 and the lower opposite sides of each annular ring 80 will extend laterally beyond the sides of the mounting bracket 160 as shown particularly in FIG. 13 so as to permit the venting of air from the inside of each cylindrical sleeve 62 to relieve pressure therefrom particularly when the axial plungers 64 and 66 are retracted, as above discussed.
Reference is now made particularly to FIGS. 9-13. Suitable air tubing of metal or the like generally indicated at 178c is connected to the compressed air source by means of a suitable commercially available pressure reduction device 48v whereby air is fed at a low pressure through tubing 178c and via air couplings 124 and 126 to and through tubing 178 to each of mold core assemblies 42 and 44. The flexible tubing 178 suitably connected to and extending from the outlet end of air couplings 124 and 126 is passed through an aperture 180 in the top end surfaces 55 of each of mold cores 49, is "snaked" around the assembly cylinder 62 in each of mold core assemblies 42 and 44, and is connected in series to a pair of nipples 184 which are threaded in apertures in each assembly cylinder 62 so that air will pass through flexible tubing 178 to the inside of cylinders 62 of each mold core assembly 42 and 44. See especially mold core assembly 44 at the right in FIG. 9. Flexible tubing 178 is connected by nipples 184 in like manner to both mold core assemblies 42 and 44 and operation thereof is the same for both assemblies 42 and 44. When the axial plungers 64 and 66 of the mold core assemblies 42 and 44 are retracted during biaxial CM block casting process, it is necessary to assure that all axial plungers 64 and 66 are fully retracted so that all parts thereof are totally disposed inside of walls 53 and 53a of the mold cores 49 before the CM block 30b is stripped from the mold 52 by the compression/stripper shoe. The nipples 184 connected to flexible air lines 178 are located so that the aperture in each nipple 184 extending to the inside of assembly sleeve 62 will be blocked off by the "inner ends" of axial plungers 64 and 66 when those plungers are in fully retracted position, as shown particularly in mold core assembly 44 at the right of FIG. 9. The nipples 184 in cooperation with their associated air lines 178 serve as "air sensors" for axial plungers 64 and 66 in each of mold core assemblies 42 and 44 to determine whether each and all said plungers 64 and 66 are fully retracted to inside mold core 49 as shown in mold core assembly 44 at the right of FIG. 9. That is because if all said axial plungers 64 and 66 are fully retracted there will result a sufficient predetermined back pressure (e.g., 15 psi or the like) which is measured by a suitable commercially available pressure gauge 48g that is connected to the low pressure line 178c on the input side of air coupling 124 and is mounted on CM casting machine 48 where it can be conveniently observed by the machine operator. Thus, if such back pressure via nipples 184 and air lines 178,178a is above a predetermined psi level, that indicates that the axial plungers 64 and 66 are fully retracted so that the CM block casting operation can be continued. On the other hand, if all the axial plungers 64 and 66 are not fully retracted, air will pass via air lines 178 through nipples 184 into assembly cylinders 62 and out of vents 152 in the underside thereof; and this will cause a low and insufficient back pressure reading at the pressure gauge 48g in line 178c on the input side of air coupling 124, thereby indicating that one or more of axial plungers 64 and 66 are not sufficiently retracted. Further, such "air sensor" arrangement for determining full retraction of plungers 64 and 66 by means of nipples 184 and air lines 178,178a is also used (i) to discontinue operation of the casting machine 48 if any axial plungers 64 and 66 are not fully retracted or (ii) to permit continued operation of the CM casting machine 48 if the axial plungers 64 and 66 are fully retracted, as further described below.
Referring to FIG. 13, the portion of conventional CM casting machine 48 shown in that drawing is made from a press-through of a photograph of a Columbia Machine Model 5 (one of many CM casting machines all utilizing analogous technology) made by Columbia Machine, Inc., located in Vancouver, Wash. ("Columbia"). This model Columbia machine makes one block at a time, at the rate of one block about every six seconds. Columbia, however, also makes similar CM casting machines operating in similar manner but which can produce three, six or even 12 CM blocks at a time (a three-block casting machine is believed most commonly used in the U.S.A. CM block making industry). Such Columbia machines, exemplified by Columbia Machine Model 5, have both a manual and automatic cycle operating mode. For the automatic cycle operating mode, the casting machine has a control panel incorporating electromechanical control circuitry to operate the machine in a conventional cycle. In a conventional CM block casting process, conventional mold cores similar to cores 49 but having four planar side walls would be used in a conventional manner well known in the art. The control circuitry of casting machine provides a logic pattern for conventional CM casting whereby: (1) the compression/stripper shoe 56 is lifted upwardly above the level of the feed tray 58 and a pallet 60 is raised to form the bottom of mold 52; (2) the feed tray 58 moves in over the mold 52 below the compression/stripper shoe 56; (3) CM mix 70 is fed into the cavity of the mold 52 from the feed tray 58; (4) the feed tray 58 is laterally withdrawn from over the mold 52 permitting the compression/stripper shoe 56 to come down and compress CM mix 70 in the mold 52 as vibration of mold 52 proceeds by conventional means incorporated in CM casting machine 48; (5) the compressed CM material formed into a conventional CM block is then stripped from the cavity of the mold 52 by simultaneous downward motion of compression/stripper shoe 56 and the bottom pallet 60; (6) the compression/stripper shoe 56 returns upward past the mold cores while the newly made conventional CM block 30 is being ejected on its individual pallet 60 onto a conveyor; (7) after the compression/stripper shoe 56 moves upwardly out of and above the mold 52, the above-discussed steps (1) to (6) are then repeated to carry out the next cycle for molding the next conventional block 30 in like manner as just described above herein. Note that in such a conventional CM block casting process there is no step corresponding or analogous to that shown in FIGS. 2-6.
To use the biaxial casting apparatus and process disclosed herein in a conventional block casting machine 48, there is provided a suitable commercially available electromechanical control means 48c for the suitable commercially available three-way valve 48v as part of the compressed air control means so as to alternately supply compressed air from a compressed air source to conduit 144 whereby such compressed air passing through tubing 128 to manifold hole 109 will cause axial plungers 64 and 66 in both mold core assemblies 42 and 44 to extend simultaneously. Also, said electromechanical compressed air control means 48c is caused to alternatively operate the three-way valve 48v to alternately supply compressed air to conduit 146 and thus via tubes 132 to hole 108 in manifold 78 so as to simultaneously cause retracting of all plungers 64 and 66 in mold core assemblies 42 and 44. The electromechanical control means 48c for the three-way valve 48v (or other equivalent conventional means) for alternately feeding compressed air from the source to input line 144 (to extend all axial plungers 64 and 66) or to input line 146 (to retract all axial plungers 64 and 66) are appropriately tapped into the electrical control circuitry in the control box 48c of the machine 48 to modify the machine's automatic operations logic pattern so as to modify the machine's typical above-discussed conventional molding cycle to the biaxial CM casting cycle shown in FIGS. 2-8 and fully described above. Thus the electromechanical means for controlling the three-way valve (or other equivalent means) is tapped into the control circuitry of casting machine 48 to modify its logic whereby: (a) compressed air is fed to line 146 to simultaneously positively retract axial plungers 64 and 66 in both mold core assemblies 42 and 44 as the compression/stripper shoe 56 is raised to above the feed tray 58 and the pallet mold 60 is raised to form the bottom of the mold 52; (b) compressed air is then supplied by activation of the three-way valve to input conduit 144 to cause the axial plungers 64 and 66 to be simultaneously positively extended and to remain in such extended position for the phases of the biaxial CM casting process shown and described above; (c) upon stoppage of the vibration subcycle, the three-way valve is switched to supply compressed air to input conduit 146 to cause the axial plungers 64 and 66 to move to simultaneously positively retract after the CM block 30b is formed, and to maintain said plungers in fully retracted position within the walls of mold cores 49 as shown in FIG. 11 before the compression/stripper shoe 56 and pallet 60 are permitted or caused to be moved downward to the bottom of the box to strip the completed CM block 30b from the mold 52; (d) the compression/stripper shoe 56 is raised up past the mold cores 49 and the fully retracted axial plungers 64 and 66 disposed inside the walls of mold cores 49 while the just-made CM block 30b is moved to a conveyor on its pallet 60 and a new pallet 60 is moved in below the mold 52 to provide a new mold bottom; and (e) the CM biaxial mold process and phases thereof shown in FIGS. 2-8 is thereafter repeated.
The portion 178a of the low pressure third air line 178,178a which extends from the input side of the air coupling 124 is connected to a suitable commercially available pressure gauge 48g to indicate to the machine controls whether the back pressure of air at nipples 184 and in lines 178,178a is (1) equal to or greater than a predetermined minimum back pressure (e.g., 15 psi), thereby indicating machine logic circuitry that the axial plungers 64 and 66 are fully retracted, or (2) is below such predetermined minimum back pressure, thereby indicating machine logic that one or more of axial plungers 64 and 66 are not fully retracted. In the latter case (2), the machine logic stops the machine 48. The pressure gauge is connected to a pressure-operated switch responsive to gauge movement and which switch is in turn tapped into the control circuitry of the casting machine 48 to operate as a "go-no go" addition to the machine's control system so that after a CM block 30b has been formed as shown in FIG. 1, the machine will not proceed with stripping of the block 30b and removal of the pallet 60 unless all axial plungers 64 and 66 move to fully retracted position as shown in FIG. 7 and in assembly 44 at the right of FIG. 9. If all axial plungers 64 and 66 are thus fully retracted the thus-modified machine 48 will proceed with the next phase of the block casting cycle involving removal of the CM block 30b as shown in FIG. 7, and then automatically proceed with additional CM block making cycles as shown in FIGS. 2-8 as hereinabove described. However, if all axial plungers 64 and 66 are not fully retracted when they should be, the thus-modified machine 48 will not proceed with the next phase of the biaxial CM casting process; the operator will then determine and fix the problem. Preferably, visual indicators respectively wired to the plungers provide indication to the operator as to which of the plungers is jammed.
The operating program and logic governing the conventional block-making automatic cycle of machine 48 exemplified by Columbia Machine Model 5 is shown in Columbia drawing No. D-328-30-52-1 titled "Control Schematic, Model 5 Block Machine, Stepper Controlled Oscillation". The aforementioned electromechanical controls for operating the three-way valve 48v for alternately supplying air to input conduit 144 to extend all axial plungers 64 and 66 or to input conduit 146 to retract all axial plungers 64 and 66, and the aforementioned pressure-operated switch connected to low pressure input line 178c are suitably tapped into the control arrangement shown in said Columbia drawing to modify the logic and operating program governing conventional automatic operation of the casting machine so as to perform automatic operation of the biaxial CM casting process of FIGS. 2-8 as herein disclosed.
As will be apparent to one skilled in the art in light of the disclosure and detailed explanation herein of the biaxial CM casting apparatus and biaxial CM casting method of the present inventions, although the same are explained by way of example as used in a Columbia Machine Model 5 casting machine having only one mold, such new biaxial casting apparatus can be installed in like manner in commercially available machines having three molds, six molds or any number of molds by using for such multiple molds an equal number of mold core systems generally indicated at 41 including mold core assemblies 42 and 44 and core bar and mounting assembly 46.
While the foregoing biaxial casting apparatus functions satisfactorily in the aforementioned intended manner, extensive experimental use has uncovered a number of problems. For example, the feature of single wiping seals 102 between the outer periphery of the plunger 106 and the inner periphery of sleeve 62 may not function satisfactorily, under certain operating conditions, in preventing dirt and CM material from entering the interior of the sleeve along the outer periphery of the plunger. Upon intrusion into the plunger interior (i.e., the space formed between the end face of the plunger and opposing end face of ring 80), this dirt can cause plunger jamming and can also interfere with and cause abrasion of various working parts such as abrasion of manifold 78 and pin 158. Dirt and dust can also enter the sleeve interior through vents 152.
It is accordingly one object of the present invention to prevent entry of dirt and CM material into the interior of the critical parts (i.e., parts which may jam or malfunction) of the mold core assembly.
Another object of the invention is to prevent abrasion of the working parts within the sleeve of the mold core assembly, such as abrasion of the manifold exterior surface in sliding sealing contact with the piston head of the plungers as well as abrasion of the pin movably disposed within the vacuum breaking passage of the plungers.
Another object of the invention is to avoid plunger jamming by preventing dirt from entering the interior of the sleeve between the outer periphery of the plunger and the inner periphery of the sleeve in sliding sealing contact with the plunger outer periphery.
Still another object of the invention is to prevent dirt and dust from entering the sleeve interior through the vents formed in the bottom of the sleeve.
During retraction of the plungers, air is supplied only through passage 154 and hole 156 to break the vacuum between the outer periphery of the plunger and the CM material in suction contact therewith. Since only a limited amount of air can be supplied through passage 154 and hole 156, the plunger reaction times are slow which reduces production output since the formed CM block cannot be stripped from the mold until the plungers completely retract to within the periphery of the mold cores. Plunger retraction is also prolonged due to the volume of air within the sleeve interior which must be displaced by the retracting plunger and the inadequate venting of such air through vents 152.
Still another object of the invention is to improve venting conditions within the sleeve interior so as to provide depressurization within the mold core to improve the plunger reaction times and provide for earlier release of the plungers from the mold cavities.
In the foregoing biaxial CM casting apparatus, the manifold 78 has a relatively large outer diameter in comparison with the diameter of the piston head 87 or the outer diameter of the plunger. In the foregoing apparatus, the disclosed ratio between the outer diameter of manifold 78 and the outer diameter of plunger 106 is approximately 1:2. This large diameter manifold member 78 reduces the effective surface area of piston 87 in the retraction mode of the plungers which therefore results in reduced retraction forces and prolonged retraction times, not to mention the additional weight added to the overall mold core system by the larger diameter manifolds.
Another object of the invention is to increase the retraction force utilized to retract the plungers to within the mold core peripheries and thereby improve retraction times.
Yet another object is to improve retraction times without increasing the pressure of air supplied through the mold core to extend and retract the pistons, without the use of larger size and more expensive compressors.
Another object of the invention is to reduce the overall weight of the biaxial mold core assemblies.
In the disclosed embodiment, the plungers are operated to extend through their entire stroke so as to ensure contact between their end faces 67 and the inner surfaces of the mold box walls which thereby cause openings 40 to extend entirely through the CM block walls or webs. The disclosed arrangement precludes the formation of indentations (which define "knock-outs") of reduced thickness in relation to the CM block walls or webs. The employment of knock-outs is desirable to enable the user to selectively form openings in different walls and/or webs of the CM block depending upon the manner in which the block is to be used during construction as will be described more fully below. As used herein, "knockouts" are depressions formed in the wall or web of the block which correspond in cross section to the cross section of the plunger.
Another object of the invention is to selectively control the plunger stroke so as to form knock-outs in selected walls and/or webs of the CM block during the casting process.
A further object is to form indentations on exterior faces of a CM block, for decorative or architectural relief purposes, such as by exterior placement of the plunger.
In the aforesaid mold core assembly, the core bar 72 is of solid, non-hollow construction with the pneumatic lines carried atop the core bar exposed to the working environment and thereby subject to damage. The pneumatic lines are coupled via air coupling blocks 126 to the manifold 78 within the mold core sleeves 62 via lines 128, 132 and 172 extending between the mold cores and coupling blocks. This arrangement disadvantageously increases the number of fittings necessary to communicate the source of compressed air with the manifold arrangement within the mold cores.
Another object of the present invention is to protectively shield the pneumatic lines extending from a source of compressed air to within the mold core assemblies to prevent damage to the lines as a result of exposure to a rugged and hostile environment.
Another object of the invention is to reduce the overall weight of the biaxial mold core assemblies by reducing the weight of the core bar.
Still a further object of the invention is to reduce the number of pneumatic fittings and therefore reduce the cost of the biaxial mold core assemblies and the possibility of disconnection at the fittings.
Still a further object is to improve the venting of pressurized air within the cartridge sleeves of the mold core assemblies by creating a venting path through the hollow core bar in communication with the interior of the mold core sleeves through the venting slots.
As a result of the extensive testing and experimentation of a prototype of the biaxial concrete casting apparatus embodying the foregoing invention, it was discovered that the geometry of the biaxial block imposed new flow constraints on the material being fed into the mold box, and consequently, the process was found to be sensitive to aggregate type and mix design of the CM material, parameters which are not easy to control as demonstrated by the wide variations in gradation and flow characteristics of block mixes across the country. For example, flow cracks were by far the most damaging and obvious quality defects encountered in the manufacture of early biaxial blocks, particularly as applicable to the use of lightweight aggregates in the Southern United States. These cracks were visible at around 4 and 8 o'clock around the biaxial opening, evidencing the difficulty encountered by the material to flow under the biaxial plunger. Another problem is transverse bulging of the blocks which results when material flow was enhanced through the increase of the water content in the mix, or the addition of flow admixtures, in order to minimize the cracks around the lower hemisphere of the biaxial hole. In these cases, the "green" product becomes more plastic, and is deformed by the thrusting forces imparted horizontally from the arching action of the material above the biaxial hole.
Yet another object of the present invention is to reduce flow cracks within the finished cast product as well as transverse bulging.
Still another object of the invention is to reduce flow cracks and minimize transverse bulging by modifying the cross-sectional plunger shape to increase the vertical flow channels on either side of the plunger and thereby simultaneously buttress the arch above the biaxial opening against the horizontal thrust of the suspended material.
As mentioned above, the strike off bar is operated to remove excess CM material projecting above the top end walls 55 of the mold core assemblies prior to compression and stripping of the block with compression stripper shoe 56 as depicted in FIGS. 3-6. Since the lower scraping edge of the strike off bar is an uninterrupted straight edge, extensive experimentation has revealed that, due to the biaxial geometry within the mold cavities (i.e, around the extended plungers), insufficient CM material fills the cavities beneath the plungers. Voids are therefore created.
Yet another object of the present invention is to ensure that sufficient concrete material fills the cavities to prevent voids.
Still another object of the invention is to modify the scraping edge of the strike off bar so that additional CM material extends upwardly above the top end wall of the mold cores following removal of excess material with the strike off bar whereby the additional material is thereafter compacted into the mold cavities by the compression/stripper shoe to fill any voids within the cavity, particularly beneath the plungers.
One of the most important features of my above-described prior invention relates to the logic and related mechanism for ensuring that the plungers completely retract within the periphery of the mold cores prior to stripping of a cast CM block from the mold with the compression/stripper shoe. In my prior invention, a nipple 184 mounted adjacent housing sleeve 62 is supplied with low pressure air through conduits 178 in a position to be blocked by the exterior surface of the plunger in the fully retracted position. In the fully retracted position of a plunger 66, the nipple 184 acts as an air sensor since the resulting blockage of the nipple by the fully retracted plunger raises the pressure within line 178 which is sensed by the pressure gauge/switch connected to the low pressure line. If the orifice of nipple 184 remains open (i.e., the plunger has not fully retracted to block the orifice), this pressure condition is sensed by the pressure gauge/switch to prevent the compression/stripper shoe from stripping the block from the mold as aforesaid.
In my prior invention, low pressure air is supplied to the low pressure line 178 through the same compressor supplying pressurized air to the lines 144,146 used to extend and retract the pistons. By using the same compressor and motor, it was discovered that drift (i.e., pressure fluctuations) necessitated daily recalibration of the pressure gauge so as to ensure precise monitoring of low pressure and high pressure conditions within predetermined constant pressure ranges. Failure to recalibrate on a daily basis resulted in unreliable operation of the foregoing fail-safe system.
Another object of the invention is to improve the operation of the fail-safe system for determining whether the plungers have completely retracted into the mold cores.